The present invention relates generally to refrigeration systems and, more specifically, to refrigeration systems that use a Stirling cooler as the mechanism for removing heat from a desired space. More particularly, the present invention relates to a glass door merchandiser for vending and for chilling beverage containers and the contents thereof.
Known refrigeration systems generally have used conventional vapor compression Rankine cycle devices to chill a given space. In a typical Rankine cycle apparatus, the refrigerant in the vapor phase is compressed in a compressor so as to cause an increase in temperature. The hot, high-pressure refrigerant is circulated through a heat exchanger, called a condenser, where it is cooled by heat transfer to the surrounding environment. As a result, the refrigerant condenses from a gas back to a liquid. After leaving the condenser, the refrigerant passes through a throttling device where the pressure and the temperature are reduced. The cold refrigerant leaves the throttling device and enters a second heat exchanger, called an evaporator, located in or near the refrigerated space. Heat transfer with the evaporator and the refrigerated space causes the refrigerant to evaporate or to change from a saturated mixture of liquid and vapor into a superheated vapor. The vapor leaving the evaporator is then drawn back into the compressor so as to repeat the refrigeration cycle.
One alternative to the use of a Rankine cycle system is a Stirling cycle cooler. The Stirling cycle cooler is also a well-known heat transfer mechanism. Briefly described, a Stirling cycle cooler compresses and expands a gas (typically helium) to produce cooling. This gas shuttles back and forth through a regenerator bed to develop much greater temperature differentials than may be produced through the normal Rankine compression and expansion process. Specifically, a Stirling cooler may use a displacer to force the gas back and forth through the regenerator bed and a piston to compress and expand the gas. The regenerator bed may be a porous element with significant thermal inertia. During operation, the regenerator bed develops a temperature gradient. One end of the device thus becomes hot and the other end becomes cold. See David Bergeron, Heat Pump Technology Recommendation for a Terrestrial Battery-Free Solar Refrigerator, September 1998. Patents relating to Stirling coolers include U.S. Pat. Nos. 5,678,409; 5,647,217; 5,638,684; 5,596,875; and 4,922,722, all incorporated herein by reference.
Stirling cooler units are desirable because they are nonpolluting, efficient, and have very few moving parts. The use of Stirling coolers units has been proposed for conventional refrigerators. See U.S. Pat. No. 5,438,848, incorporated herein by reference. The integration of a free-piston Stirling cooler into a conventional refrigerated cabinet, however, requires different manufacturing, installation, and operational techniques than those used for conventional compressor systems. See D. M. Berchowitz et al., Test Results for Stirling Cycle Cooler Domestic Refrigerators, Second International Conference.
To date, the use of Stirling coolers in beverage vending machines, GDM""s and dispensers is not known. Therefore, a need exists for adapting Stirling cooler technology to conventional beverage vending machines, GDM""s, dispensers, and the like.
The present invention thus may provide a refrigeration apparatus driven by a Stirling cooler and having reduced internal vibrations. The apparatus may include an insulated enclosure. The enclosure may define an opening from the inside to the outside. A heat-conducting member may be disposed within the enclosure and in alignment with the opening. The apparatus may further include a Stirling cooler. The Stirling cooler may be selectively connectable to the heat-conducting member. A cushioning member may be disposed between the heat-conducting member and the enclosure, such that vibrations from the Stirling cooler to the enclosure are reduced.
Specific embodiments of the invention include the use of a Stirling cooler having a hot portion, a regenerator portion, and a cold portion. The cold portion may be in axial alignment with the hot portion and the regenerator portion. The regenerator portion may be disposed between the hot portion and the cold portion. The cold portion may include a larger diameter that the regenerator portion. The cold portion thus may include a flange that extends outward in a radial direction for a distance greater than the diameter of the regenerator portion.
The cushioning member may include an elastomeric member, a compliant foam, a low durometer polyurethane, a Sorbothane polymer, a rubber material, or similar types of materials. The cushioning member may be in the form of a toroidal element, a gasket, or similar shapes. The heat conducting member and the cold end of the Stirling cooler may be connected by a number of screws. The screws may use an elastomeric washer. The opening may include an indentation. The cushioning member may be positioned within the indentation.
A further embodiment of the present invention may provide an enclosure refrigerated by a refrigeration system having a Stirling cooler and a heat-conducting member. The enclosure may include a number of walls with one of the walls having an aperture therein. The refrigeration system may be positioned about the aperture. A cushion member may be positioned between the wall and the refrigeration system.
The cushioning member may include an elastomeric member, a low durometer polyurethane, a Sorbothane polymer, or similar materials. The cushioning member may be a toroidal element. The aperture may include an indentation positioned therein. The aperture may include a predetermined diameter. The predetermined diameter may permit the Stirling cooler to pass through and may or may not allow the heat-conducting member to pass through.
The one wall may be the bottom wall. The cushioning member may be positioned within the indentation. An insulated plug may be positioned between the Stirling cooler and the cushioning layer. The insulated plug and the cushioning element may form a seal therebetween.
The one wall also may be the top wall. An elastomeric ring may be positioned within the indentation. A sealing plate may be positioned within the indentation. The cushioning element may include a number of springs or other types of dampening devices positioned between the Stirling cooler and the sealing plate. A sealing ring may be positioned between the sealing plate and the Stirling cooler.
A further embodiment of the present invention may provide for an enclosure. The enclosure may include a number of walls defining an interior space. One of the walls may include an aperture therein. A Stirling cooler may be positioned within the aperture. A heat-conducting member may be attached to the Stirling cooler and positioned within the interior space. A cushioning member may be positioned between the wall and the heat-conducting member.
The wall may be the bottom wall. The cushioning member may include an elastomeric member, a Sorbothane polymer, or similar types of materials. The aperture may include an indentation positioned therein. The cushioning member may be positioned within the indentation. The aperture may include a predetermined diameter. The predetermined diameter may permit the Stirling cooler to pass through but prohibit the heat-conducting member from passing therethrough. An insulated plug may be positioned between the Stirling cooler and the cushioning layer. The insulated plug and the cushioning member may form a seal therebetween. An attachment ring may connect the Stirling cooler and the heat-conducting member.
A further embodiment of the present invention may provide for an enclosure. The enclosure may include a number of walls defining an interior space. One of the walls may include an aperture therein. A Stirling cooler may be positioned about the aperture. A heat-conducting member may be attached to the Stirling cooler and positioned within the interior space. A dampening device may be attached to the Stirling cooler and the one wall so as to absorb the vibrations produced by the Stirling cooler.
The wall may be the top wall. The dampening device may include a number of springs. The wall may include a sealing ring positioned within the aperture. The aperture may include an indentation positioned therein. An elastomeric ring may be positioned within the indentation. The aperture may have a predetermined diameter. The predetermined diameter permits the heat-conducting member to pass through. A sealing ring may be positioned between the sealing plate and the Stirling cooler.
These and other objects, features, and advantages of the present invention will become apparent after a review of the following detailed description of the disclosed embodiments and the appended drawing and claims.